US 7,482,180 B1
Method for determining the impact of layer thicknesses on laminate warpage
Julien Sylvestre, Chambly (Canada); Jean Audet, Granby (Canada); Marco Gauvin, Granby (Canada); and Sylvain Pharand, St-Bruno (Canada)
Assigned to International Business Machines Corporation, Armonk, N.Y. (US)
Filed on Apr. 29, 2008, as Appl. No. 12/111,196.
Int. Cl. H01L 21/66 (2006.01)
U.S. Cl. 438—15  [438/125; 257/E21.525] 1 Claim
OG exemplary drawing
 
1. A method to analyze the warpage of organic laminates used in flip-chip packaging, the method comprising:
providing a plurality of organic laminates, each laminate comprising a plurality of layers;
collecting warpage data by measuring the warpage of each laminate;
gathering thickness data by measuring layer thicknesses of each laminate at several different points of each laminate;
performing a principal components analysis on the thickness data to calculate orthogonal basis vectors to re-express the thickness data in a different basis;
projecting the thickness data for each laminate onto the orthogonal basis vectors;
forming a linear model expressing the warpage data for each laminate in terms of the projection of corresponding thickness data onto the orthogonal basis vectors, each projection multiplied by a weight;
analyzing the weights to determine the contribution of each orthogonal basis vector to the variance of the warpage data; and
interpreting the contribution and structure of each orthogonal basis vector to estimate the importance of each layer or combination of layers in contributing to the warpage of the laminates.