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Method for a recursive die-attach monitor

IP.com Disclosure Number: IPCOM000020156D
Publication Date: 2003-Oct-29
Document File: 3 page(s) / 153K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a recursive die-attach monitor. Benefits include improved functionality.

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Method for a recursive die-attach monitor

Disclosed is a method for a recursive die-attach monitor. Benefits include improved functionality.

Background

         Die attach is one of the most difficult steps in conventional stacked chip scale package assembly. Inadequate control of die attach, causes reliability issues. As a result, bond-line thickness (BLT) is must be measured and controlled accurately. A common practice of in-line bond-line thickness (BLT) measurement involves measuring die height on a measuring scope and subtracting wafer thickness from the measured height. Although die height can be accurate measured, the BLT is not accurately estimated due to substrate and die warpage are not accounted for and subtracted wafer thickness is an average value.

General description

         The disclosed method proposes monitoring the minimum die height as an indicator of BLT quality. Specifically, the disclosed method proposes an algorithm to establish statistical process control (SPC) of minimum die height and maximum die tilt at each die of a stacked package. It further proposes monitoring the maximum overall die height to provide quantitative measurement of mold clearance.

Advantages

         The disclosed method provides advantages, including:
•         Prediction and prevention of excursions due to enabling the recursive statistical process control of accurately measure minimum die height and maximum die tilt on a multiple-die stacked package
•         Prediction and prevention of excursions due to providing an overall quantitative measure of mold clearance

Detailed description

         The disclosed method includes a recursive algorithm that processes data about the substrate, the i-th die, and the total stack height (TSH). The variables i and I designate the iteration numbers for the algorithm’s processing.

Substrate

         The disclosed method measures four points on the substrat...