Patent ID: 7467076
Filing Date: 2008-12-16
Classification: G06F

Abstract:
1. An apparatus for predicting reliability in an electronic device package, comprising: a package modeling database storing data concerning a shape of an electronic device package and specifications for modeling the electronic device package; a material property database storing data concerning material properties of the electronic device package; a parameter designating unit receiving parameters inputted to designate a type of the electronic device package, dimensions of the shape thereof, material thereof and properties of the material, and assessment conditions thereof; a modeling unit creating a simulation model of the package on the basis of the inputted parameters of the properties of the material, and the dimensions of the electronic device package, which are designated by using the inputted parameters; a simulation executing unit using the simulation model, which is created by the modeling unit, to execute a simulation under the conditions designated by the inputted parameters; a results-of-simulation assessing unit assessing the results of the simulation executed by the simulation executing unit on the basis of a predetermined assessment criterion, and storing and preserving, in a results-of-assessment database, the inputted parameters and results of assessment which are obtained by the assessing the results of the simulation, with regard to each type of electronic device package; an assessment expression generating unit generating, as an assessment expression, an approximate expression, which infers the results of assessment from the inputted parameters, on an assumption that a predetermined amount of the results of assessment is preserved in the results-of-assessment database; and an assessment predicting unit, when an electronic device package in which the assessment expression has already been established is designated by using the inputted parameters, outputting the results of an assessment prediction according to the assessment expression; wherein an orthogonal polynomial expression, based on a design of experiments method, is used to generate an initial assessment expression in establishing the assessment expression, and the assessment expression is updated on the basis of the least squares method; when a number of combinations of the inputted parameters and the results of assessment obtained by carrying out a simulation which is concerned with the same type of electronic device package exceeds a number of the inputted parameters, comprising a sum of the number of the inputted parameters representing dimensions, a number of material properties, and a number of conditions for a load, an assessment expression generating unit produces an assessment expression (E) as an approximate expression that makes the inputted parameters approximate the results of assessment, the assessment expression production unit being implemented by running a predetermined program, residing in the computer system, wherein maximum stress SA is approximated by a quadratic polynomial expression, or an orthogonal polynomial expression, as follows: wherein ΔT denotes difference in temperature, a 0 , a 1 , a 2 , b 1 , b 2 , etc., d 1 , and d 2 denote unknown coefficients, as to which, if a number of combinations of the inputted parameters and the results of assessment of the maximum stress SA, which is the same as the number of unknown coefficients, is obtained, the unknown coefficients are uniquely determinable and, if the number of the above combinations exceeds the number of unknown coefficients, the unknown coefficients are predictable according to the least squares method.